The devices layer relates to the disk and controllers that store your data. Adaptive Server can manage a virtually unlimited number of devices.
Issues at the devices layer include:
The distribution of system databases, user databases, and database logs across devices
Whether partitions for parallel query performance or high insert performance on heap tables are necessary
Address these issues by:
Using more medium-sized devices and controllers; doing so may provide better I/O throughput than a few large devices
Distributing databases, tables, and indexes to create even I/O load across devices
Using segments and partitions for I/O performance on large tables used in parallel queries
Adaptive Server devices are mapped to operating system
files or raw partitions, and depend on the performance of the underlying
physical devices and disks. Contention can occur at the operating
system level: controllers can be saturated and the disks organized
under storage area network logical unit numbers (SAN LUNs) can be
over-worked. When analyzing performance, balance the physical load
to properly distribute load over operating system devices, controller,
storage entities, and logical unit numbers.
